Clutch installation for motor vehicles



CLUTCH INSTALLATION FOR MOTOR VEHICLES ,E BYZTM ORNEY March 24,1953 w. F. WILSON 2,632,543

CLUTCH INSTALLATION FOR MOTOR VEHICLES Filed April 4, 1947 2 SHEETSf-SHEET 2 vehicle.

Patented Mar. 24, 1953 CLUTCH INSTALLATION FOR MOTOR VEHICLES William F. Wilson, Wauwatosa,I Wis., assigner to Allis-Chalmers Manufacturing Company, Milwaukee, Wis., a corporation of Delaware Application April 4, 1947, Serial No. 739,279

7 Claims. (Cl. 19.2-69) The invention relates to clutch installations,

and it is concerned more particularly with animproved clutch con-trolled mechanism for transmitting engine power to the running gear of a motor vehicle.

vIn motor vehicles such as crawler tractors,

which are steered by driving it has heretofore g been usual to mount a pair of steering clutches in a transmission housing which also encloses gearing for transmitting power rto the steering mitting power from the steering clutches to traction devices at opposite sides of the vehicle. In order to properly service such vehicles when Ip-arts of the clutch installation, or other parts such as the final drive pinions have become worn and require replacement, it is usually necessary to dismantle the clutch installation, and attempts have heretofore been made to reduce the amount of time and labor required for such servicing of the However, the constructions which have been evolved as a result of such previous attempts are believed to have not been entirely successful in accomplishing the desired results without sacricing certain other requirements which are essential from anV engineering and performancey Y standpoint. i

Generally, it is an object ofthe invention to provide an improved clutch installation for ymotor vehicles, which will take `care of the requirement l loading mechanism therefor are combined to form an assembled unit which may be moved bodily into and out of installed position, and in which f a shift collar for rehearsing the clutch disks from the pressure of the loading mechanism, is so arranged that the mentioned assembled unit can .be moved into and out of installed position without requiring dismounting of the shift collar from its installed position.

A further object of the invention is to provide l a readily connectable and disconnectable precision mounting for a clutch unit of the mentioned character, which will center such unit in the installation with a high degree of accuracy and thereby V insure eflicient and trouble-free functioning of the installation under severe operating Vconditions such as are encountered in heavy duty motor Vehicles, and more particularly in connectionwi-th the steering clutches of a crawler tractor.

A further object of the invention is to providev 2 an improved clutch installation of the characte set forth incorporating a multiple disk clutch assembly and in which said clutch assembly is properly ventilated for adequate heat dissipation.

A further object of the invention is to provide an improved clutch installation of the hereinbefore mentioned character, which is rela-tively sim- .ple and which, in particular, does not require an intermediate shaft between the driving and driven shafts of the installation.

A further object of the invention is to provide an improved steering clutch installation for motor vehicles, which affords ready removal not only of the steering clutches but also of the gearing through which power is transmitted to and from the steering clutches.

A further object of the invention is to provide a steering clutch installation of the above mentioned character, in which a clutch assembly and a throw-out mechanism therefor are arranged in an axially space saving relation to each other, so that the transmission housing which usually encloses la pair of such clutch assemblies and throwout mechanisms may be kept at a desirably short transverse width.

These and other` objects and advantages are l attained by the present invention, various novel features of which will be apparent from the description herein and from the accompanying drawings disclosing an embodiment of the invention, and will be more particularly pointed out in the appended claims.

In the drawings:

Fig. 1 is a View of a steering clutch and gear installation for a crawler tractor, the installation being shown in section on a vertical transverse a plane through the tractor;

Fig. 2 is an elevational View taken in the same direction as Fig. 1, and showing a clutch unit of the installation in partly removed condition; and

Fig. 3 is a View taken on line III- III of Fig. 2 and showing parts of a clutch throw-out mechanism.

The mechanism shown in Fig. 1 is intended for .transmitting driving power to a conventional track mechanism of a crawler tractor, and while such a tractor as va whole is not shown in the drawings, it will be understood that it is equipped with two such track mechanisms, one at each side, and that the clutch installation shown in the Adrawings relates to the track mechanism at the left side of the tractor. A second clutch installation conforming with the principles of construction and operation disclosed herein is preferably employed to transmit power to the track unit at the right side of the tractor, and for that purpose the parts of the clutch installation at the left side of the trac-tor which are shown in the drawings will be duplicated and correspondingly arranged at the right side of the tractor.

A transmission housing, partly shown in Figs. l and 2 and generally indicated by the reference character l, is constructed in the form of a fabricated welded structure, and comprises top and bottom walls 2 and 3, and partitions 4 and 6, the space between the top and bottom walls and para titions dening a central compartment 1. At the left side of the central compartment 1, the transmission housing has a clutch compartment 3 and a linal drive gear compartment 9., separated from each other by a vertical wall II. Apertures I2 and I3 in the top wall `2 afford access to the central compartment 1 and to the clutch compartment S, respectively, for assembly purf poses, and these apertures are normally closed by central compartment 1 and is rotatably mounted on the partitions 4 and 6 by -conical roller bearings I6 and I1. The outer race-of the roller bearing I6 abuts a bearing retainer I8 which is secured to the -partition 4 bycap screws I9, and the inner race of the bearing I3 Vabuts a shoulder `'2l of the shaft I4, the arrangement being such as to limit axial displacement of the shaft I4 to the lef-t, that is, toward the clutch compartment 8. The outer race of the roller bearing I1, on the other lhand, abuts a bearing retainer 22 which is secured to the partition 6 by cap screws 23, and

Athe inner race abuts a shoulder 24 of the shaft I4, the arrangement of the bearing I1 being such as to limit axial displacement of the shaft 'I4 toward the right, that is, toward a clutch compartment which is Yformed at the right of the central compartment 1 and corresponds to the clutch compartment 58. Shims 2'6 are interposed between the bearing retainer I8 and 'the partition 4, and between the bearing retainer 22 and the partition 6 to provide for proper adjustment of the bearings IS and I1 4which will 'rotatably secure the shaft 14 in axially 'fixed position relative to the 4housing I without appreciable axial play.

A bevel ring gear 21'within the compartment 1 Yis secured by bolts "'28 to a hub 29 which 'has a splined tapered connection 'with the shaft I4 and is retained in axially xed position by a nut 30. The bevel ring gear 21 forms part of a 'conventional mechanism, not shown, for transmitting power 'from 'the tractor motor to the driving shaft I4. Rotary shaft seals 3| of conventional construction are operatively interposed between the shaft I4 and the bearing retainers I8 land 22, re-

` 'spectively, to prevent passage of oil from the centralcompartment to the clutch compartments.

Referring to the left side of Fig. 1, a final drive pinion 32 is integrally formed with a driven shaft 33 which is rotatably mounted on the housing wall I I and on an opposite end wall 34 of the nal drive compartment 9 by means of conical roller bearings 36 and 31. The outer race of the roller bearing 31 Vabut's a bearing retainer 38 which is secured inside of the clutch compartment 8 to the wall by cap screws 39, and the inner race of the roller bearing 31 abuts the adjacent Vend of the pinion 32, the arrangement being such as to limit axial displacement of the driven shaft 33 toward the right, that is, in the direction toward the driving shaft I4. The outer race of the roller bearing 33, on the other hand, abuts a cap 4I secured to the end wall 34, and the inner race of the bearing 3S abuts an adjacent shoulder of the driven shaft 33, the arrangement being such as to limit axial displacement of the driven shaft 33 toward the left, that is, away from the driving shaft I4. Shims 42 are interposed between the cap 4I and the end wall 34 for proper adjustment of the roller bearings 36 and 31 which will rotatably secure the driven shaft 33 in axially fixed position without appreciable axial play relative to the housing I and relative to the driving shaft I4.

The pinion 32 forms part of a conventional final drive mechanism for transmitting power to a self-laying track unit, not shown, at the lef-t side of the tractor.

The bearings I6 and I1 for the driving shaft i4 and the bearings 36 and 31 for the driven shaft 33 are accurately aligne-d on a common axis, preferably by boring the seats for the outer races of those Ibearings on the housing 'I in one setting. The driving and driven shafts I4 and 33 are relatively rotatable about said common axis and have relatively opposed ends within the clutch compartment 8 at a relatively wide axial spacing from each other, the driven shaft 33 extending axially a relatively short distance into the clutch compartment 3 from the left and the driving shaft I4 extending axially a somewhat larger 4distance into the clutch compartment 8 from the right. An axially fixed driving hub member 43 is nonrotatably secured to the portion of the ldriving shaft I4 within the 'clutch compartment 8. The driving hub comprises an axially lextended sleeve portion and a radial web portion substantially in the form of a disk and which has four axial apertures 44 at a radial distance vfrom the central sleeve portion Yand equally spaced circumferentially of the driving hub member 43. The central sleeve portion of the hub member is spline ntted upon Va conical end portion of the driving shaft I4 and retained in axially fixed position by means of a thrust washer '46 `which is doweled to the driving shaft I4 and drawn up vagainst the hub member 43 Vby a cap screw `41.

An vaxially fixed driven hub member 48 is nonrotatably secured to the portion of the driven shaft 33 within the clutch compartment 8, the driven hub member `comprising an axially extended sleeve portion and a radial web portion substantially in the form of a disk and which has a number of apertures 49 (Fig. 2) at a radial distance from the `central sleeve portion and which are equally spaced circumferentially of the driven hub 48. The central sleeve portion of the driven hub is spline fitted upon a vconical end portion of the driven shaft 33 and retained in axially fixed position by means of a thrust washer 5l which is doweled to the driven shaft 33 and drawn up against the hub member 48 by a cap screw 52. A rotary shaft seal 53 of conventional construction is operatively interposed between the axially extended sleeve portion Yof the driven hub member 48 and the bearing retainer 38 to prevent passage vof lubricant from 'the Vfinal drive gear compartment 3 into the clutch compartment 8.

operatively mounted between 'the driving and vdriven hub members 43 and 48 is a friction clutch unit for selectively establishing and interrupting a driving connection between the driving and driven shafts I4 and 33, the relatively opposed ends of said shafts and the relatively opposed axially inner faces of the hub members being spaced a 'predetermined:relatively wide axial distance from each other to provide a space of suitable axial width to accomodate the clutch unit, and the latter being adapted for radial movement into and out of said space, as will be described more fully hereinbelow.

The clutch unit, as shown in the drawings, is of the multiple disk type and comprises an inner drum 54, an outer drum 56, an axially compressible assembly of driving and driven clutch disks 51 and 58, and a loading mechanism for said clutch disks which is operatively mounted `on the inner clutch drum 54. In conformity with r53' of the driven clutch disks 56. At the end of the inner drum adjacent to the driving hub member 43, an abutment flange for .the stack of Aclutch disks 51 and 58 is integrally formed with the'inner drum 54, the outside diameter of said flange being shorter than the inside diameter of -the splined portion of the outer drum 56 to permit axial movement of the outer drum 56 to the right in Fig. l over the abutment flange of the inner drum 54, such axial movement of the outer drum relative to the inner drum being accommodated by the splined connection between the driven clutch disks 58 and the outer drum 56.

The mentioned loading mechanism for the disk assembly 51, 58 comprises a thrust plate 59 and a series of axially arranged coil springs 6I which 2bear upon a radial inwardly extending flange portion of the inner drum 54 and arevconnected in thrust transmitting relation with the thrust plate 59. Forthat purpose, a series of axially slidable spacer tubes 62 are mounted in axial holes of the inwardly extending flange portion of the inner drum 5,4 coaxially with the coil springs 6l, respectively, and an abutment ring 63 within the drum 54 is drawn up against the spacers by a series of axial bolts 64, the coil springs 6l being centered on axial lugs of the abutment ring 63 and exerting pressure upon the latter, which pressure is transmitted through the heads of the bolts64 to the thrust plate 55 and eifective to compress the clutch assembly v51, 58 between the pressure plate 55 and the outwardly extending abutment flange of the inner drum 54. In the condition of the clutch unit as shown in Fig. l,

thecoil springs 6I are effective to exert the required pressure upon the disk assembly 51, 58 so as to establish a driving connection between the clutch drums through the disk assembly 51, 58. Axial inward movement of the abutment ring 63 toward the driven hub member 48 may be effected by a clutch throw-out mechanism which will be described more fully hereinbelow, and

such axial inward movement of the abutment ring will release the pressure of the thrust plate 59upon the disk assembly 51, 58 and thus be effective to interrupt the driving connection between the inner and outer clutch drums.

As vstated hereinbefore, the clutch unit com- 'prising the inner and outer clutch drums 54 and 56, the disks 51, 58 and the loading mechanism l 59, 6I, 62, 63, 64, is operatively mounted between the drivingand driven hub members V43 and 48, and for that purpose provisions are made as follows:

" At the end of the inner clutch drum 54 adjacent -to the driving hub member 43, an annular recess is formed'at the inner side of the drum rfor the receptionof an annularcentering bead 66 which is integrally formed with the hub member 43 and extends axially from the inner face of the latter. The bead 66 and the corresponding recess of the inner clutch drum 54 cooperate to center the inner clutch drum in accurately concentric relation with the common axis of the driving and driven shafts i4 and 33, and the inner clutch drum 54 is axially secured to the driving hub member 43 by detachable fastening means which are shown in the form of a circumferential series of cap-screws 61. The hub member 43 has a circumferential series of axial holes at the periphery of its radially extending web portion and the shanks of the cap screws 61 extend through these holes and are screwed into tapped holes of the inner clutch drum 54, to draw the inner clutch drum 54 axially against the driving hub member 43 and keep it in the centered position which is determined by cooperation of the centering bead 66 with the annular recess of the inner clutch drum 54.

The mounting of the outer clutch drum 56 on the driven hub member 48 is similar to the mounting of the inner clutch drum 54 on the driving hub member 43, that is, the driven hub member 48 has an annular centering bead 65 integrally formed therewith at its axially inner face and which cooperates with an adjacent inwardly extending ange of the outer clutch drum to center the latter in accurate concentric relation with the common axis of the driving and driven shafts I4 and 33. The inwardly extending iiange of the outer clutch drum also axially abuts a radially extending peripheral portion of the driven hub member 48 at the axially inner side of the latter, and the outer clutch drum 56 is axially secured in fixed position on the driven hub member 48 by detachable fastening means which are shown in the form of a circumferential series of `cap screws 68.

The clutch throw-out mechanism which has been mentioned hereinbefore is mounted in the clutch compartment 8 at the right side of the clutch unit and is constructed as follows:

A thrust collar 1I surrounding the central axially extended portion of the driving hub member 43 is connected in supported and axially slidable relation with the latter, the axially extended portion of the hub member having a cylindrical outer surface, and a cylindrical bore in a central hub portion of the thrust collar 1l having a sliding t on the cylindrical outer surface of the axially extended sleeve portion of the driving hub member 43. At its outer periphery, the thrust collar 1l has four spaced thrust ngers 12 which extend axially through the apertures 44 of the driving hub member 43 and are abuttable endwise with the abutment ring 53 of the clutch unit.

The axially extended hub portion of the thrust collar 1l carries a ball bearing 13 which in turn is mounted in an annular cage 14 surrounding the hub portion of the thrust collar 1|.

The inner race of the ball bearing 13 is press fitted upon the hub portion of the thrust collar 1I and at its axially inner end abuts a shoulder of the thrust collar 1l. The outer race of the ball bearing 13 is seated at its axially outer end lagainst a shoulder of the cage 14, so that movea .polygonal frame 1B which serves as va'shift "yoke .and which is pivotally supported on the cage 14 by means of trunnions 11 .and 1E. The trunnion 11 is mounted in a bore at one side of the shift yoke 16 and retained lin position vby a Alocking plate 19. A portion of the trunnion 11 extends inwardly of the yoke '5E into :a :hub portion of the cage 14 and in which it is rotatable about 'an axis at right angles to the common axis of the driving and driven .shafts I4 and 33. The trunnion18is similarly mounted on the shift yoke 1G and rotatably connected with the Ycage 14 at the opposite side of the latter to support the .yoke 15 for pivotal movement'relative to the cage about `the common axis of the trunnions 11, 13. It will be noted that the shift yoke 1t is thus entirely supported on the driving shaft I4, and that the connections Aat Adiarnetrically opposed Ypoints thereof with the cage 14 permit swinging movement Aof the yoke on an axis intersecting the longitudinal vaxis on which the cage 14 is rotatably connected with the thrust collar 1I.

A pair of relatively abuttable thrust buttons Si and 82 are mounted on the shift yoke 16 and on `the bearing retainer I8, respectively, below .the common axis of the driving and driven shafts i4 and 33, and the thrust buttons 8| and *82 are cooperative, upon relative engagement thereof, to limit pivotal movement of the .yoke 15 about the common axis of the trunnions 11 and 18. `A stud 83 is mounted on the yoke 1E in diametrically opposed relation to the thrust button 8l and has a ball head for cooperation with a suitable actuating mechanism, not shown, which is operable to swing the yoke 1t about the common axis of the `trunnions 11 and l.

From the foregoing explanations, it will be apparent that swinging movement of the yoke 16 in the direction of arrow A in Fig. l will be effective to release the clutch disks 51, 58 from the pressure of the coil .springs 5i, the thrust collar 1I having a short but suincient range of axial movement relative to .the driving hub member 43 to engage and disengage the clutch unit by back and 'forth movement of the yoke l5 about the axis of the trunnions 11 and 18.

IReferring to Fig. 2, Athe driving and driven hub .members 43 and 48 are shown in this figure at the .same axial spacing 'from each other vas in Fig. 1, andthe shift yoke 1&5 is also shown in the same position in which it is shown vin Fig. l and which corresponds to the fully engaged condition of the clutch unit. However, the inner 'and outer clutch drums 54 and 56 of the clutch unit are show-n in a position of axial displacement relative to each other and of `radial displacement relative tothe driving and driven hub members 43 .and 48, as compared with the showing in Fig. 1. `In order to prepare the clutch unit for movement into the position in which it is shown in Fig. 2 it is only necessary to remove the cap screws 61 shown in Fig. l from the inner clutch drum, to remove the cap screws 5S .from the outer 'clutch drum, and then slide 'the outer .clutch drum axially relative to the inner clutch drum so as vto telescope the two clutch drums into the axially contracted vrelation to each other in which they are shown in Fig. 2. `Such axial contraction of the clutch drums may be effected without interference by the disk assembly 51, E8 and without interference by the loading mechanism which is operatively mounted on the inner clutch drum and which includes the thrust plate .59, the coil springs 6I, the spacers 62, the abutment `ring 63fand the bolts E4. It will also be noted that the clutch drums 54 and 56 in their relatively contracted position as shown in Fig. 2 are entirely free of the beads 66 and 68, and that the clutch unit in its vcontracted condition has adequate clearance at both sides to permit radial movement thereof into and out of the space between the hub members 43 and 48. vThe opening I3 in the top wall 2 of the transmission housing is suitably proportioned to permit removal of Vthe clutch unit from the clutch compartment S, and a rope or belt is preferably placed around the lclutch unit in order to lift it out of the clutch compartment.

VOn the other hand, in order to install the clutch unit between the driving and driven hub members 43 and 48', the clutch unit may be lowered in its contracted condition into the space `between said hub members, and the drums 54 and r5t may then be engaged with the centering beads (it and $8, respectively, and secured in operative position. This may be clone vby rst engaging one of the drums with its respective centering bead and securing it in fixed position by installing one or more respective cap screws, and by then axially shifting the -other drum to engage it with its respective centering bead on the other hub member and securing it in axially xed position by installation of respective cap screws, The relative shifting .movement of the inner and outer clutch drums to operatively position the clutch unit between the driving and driven hub members 43 and 48 places the clutch unit into an expanded condition, and .it will be noted that the hereinbeiore mentioned loading mechanism for the clutch disk assembly 51, 58 will 'be operable in such expanded condition of the clutch unit to selectively establish and interrupt a driving connection between the inner and outer drums upon swinging movement of the shift yoke 1S in opposite directions about the axis of the trunnions 11, 18.

From the foregoing explanations, it will -be apparent that the clutch installation as shown in the drawings permits ready .removal of the clutch unit from the vdriving and driven hub members 43 and 48 without dismounting the thrust collar 1I, Ior the cage 14 or the shift yoke 16, all of which parts may remain in installed position within the clutch compartment 8. It will be .noted that this result is accomplished by arranging the clutch .unit and the throw-out mechanism in radially separable relation to each other. To provide for such separable relation, the thrust fingers 12 of Vthe lthrust collar 1i and the abutment ring G3 are arranged in endwise contacting relation to each other and suitably proportioned so that, when the clutch unit is adjusted to its axially contracted condition, as explained hereinbefore in connection with Fig. 2, the abutment ring 63 simply moves away from the thrust iingers 12 of the thrust collar 1I and the latter will not interfere with the radial removal of the clutch unit.

AUpon removal of the clutch unit from the space between the hub members 43 and 48, the cap screws 41 and 52 which retain the hub members on their respective shafts become readily accessible, and vif desired, .the installation may then further be dismantled for the purpose of removing other parts of the mechanism. If it is desired to remove the driven shaft and nal drive pinion, the hub member 48 'is preferably rst disconnected from the shaft 33 and moved out of the' clutch vcompartment 8. The cap screws 39 Y for the bearing retainer 38 are then readily accessible and may be removed in order to take out the bearing retainer' 38. The shaft 33 and the pinion 32 may then be withdrawn from the final drive compartment 9 into the clutch compartment 3 and removed through the top opening I3. When the shaft 33 is withdrawninto the clutch compartment 8, the outer race of the roller bearing 31 will be pushed out of its seat on the w-all II while the outer race of the roller bearing 36 may remain in position on the outer wall 34 of the final drive compartment 9.

In connection with the description of the driven hub member 48, it has been mentioned hereinbefore that this hub member has a circumferential series of apertures 49. These apertures in conjunction with the apertures 44 of the driving hub member 43 provide for circulation of air through the interior of the clutch unit, and it will be noted that there is ample space inside of the inner clutch drum 54 to provide for adequate dissipation of heat by such air circulation. As shown in Fig'. 2, the outer clutch drum 56 is provided with a circumferential series of holes 84 which, While assisting ventilation of the clutch unit, also facilitate turning of the clutch unit by means of a bar when it is desired tobring the cap screws 61 and 69 into easy reach from the top opening I3.

It will further be noted lthat the transverse Width of the clutch compartment 8, that is, the spacing between the partition 4 and the wall I I, which isreduired to accommodate the lentire clutch installation including the throw-out mechanism, is relatively short, and that the transmission housing I may therefore be constructed readily to meet existing requirements for a minimum over-all Width transversely of the tractor. The outer drum 56 of the clutch unit may be utilized to serve as a brake drum in the customary manner, that is, a brake mechanism, not shown, may be installed within the clutch compartment 8, for cooperation with the outer circumferential surface of the clutch drum 56.

It should be understood that it is not intended to limit the invention to the particular forms and details described hereinabove and that the invention includes'such other forms and modications as are embraced by the scope of the appended claims.

It is claimedand desired to secure by Letters Patent:

l1. A clutch installation comprising, in combination, a pair of axially spaced driving and driven elements mounted for relative rotation and in axially fixed relation to each other, 'a clutch unit adapted for radial movement into and out of the space between said driving and driven elements and comprising, axially overlapping inner andV outer clutch drums each having an axial length shorter than the axial width of said space, an assembly of selectively engageable and disengageable lannular clutch plates mounted on said inner drum in surrounding relation thereto and at a predetermined axial spacing from one end of the latter, resilient loading means for said clutch plate assemblyincluding 4an axially shiftable thrust plate within said inner drum, separable connecting means securing said inner drum at said one end thereof to one of said driving and driven elements in an axially xed position in which said inner drum extends in axially overhanging relation to said one element and terminates Within said space at a predetermined axial distance from the other of said elements, drive 10' transmitting means operatively connecting said outer drum at its inner periphery in axially shiftable relation with said clutch plate assembly, said outer drum having an end portion which in an axially adjusted operative position of said outer drum projects axially beyond said clutch plate assembly and beyond the free end of said inner drum, and said drive transmitting means permitting shifting movement of said outer drum from said axially adjusted position toward said one end of said inner drum, other separable connecting means securing said outer drum at said one end thereof in said axially adjusted position to said other element, bearing means independent of said inner and outer clutch drums and connected with one of said driving and `driven elements in nonobstructing relation to said space, and i a mechanism yfor releasing said loading means comprising a throwout collar having a hub portion supported for axial back and forth movement on said bearing means and having a thrust transmitting portion extending from said hyb portion intoI cooperative engagement with said thrust plate of said loading means.

2. A clutch installation as set forth in claim 1, in whichv one of said driving and driven elements comprises a shaft having a radially enlarged hub member; in which detachable fastening means for securing one of said drums to' said hub member operatively engage the latter at its outer periphery, and in which said throwout collar is supportedly mounted at the axially outer side of said hub member and has thrust fingers extending through said hub member at points radially between said shaft and said outer periphery of said hub member.

3. A clutch installation as set forth in claim 1,` in which one of said driving and driven elements operatively engage the latter at its outer periphery, and in which said throwout collar is supportedly mounted at the axially outer side of said hub member and has thrust fingers extending through said hub member at points radially between said shaft andsaid outer periphery of said hub member.

4. A clutch installation comprising, in combination, a support, a pair of axially spaced driving and driven elements mounted' in axially fixed positions on and for' rotation independently of each other relative to said support; a clutch unit comprising a pair of relatively rotatable axially overlapping radially inner and outer clutch parts adapted for axial contracting and expanding adjustment `relative to each vother and each havingV an axial length shorter-than the axial 'spacing between said driving and driven elements; axial, radial and torqueload transmitting separable connecting means associated withvand operative to detachably secure said inner clutch part to one of said driving and driven elements in anaxially xed position in which said inner clutch part extends axially from saidone element toward and is spaced a predetermined axial distance from the other of said driving and driven elements; other axial, radial and torque load transmitting separable connecting means associated with and operative to detachably secure 'said outer clutch part to the other of said driving i and driven elements in an axially xed position in which said outer clutch part extends axially from said other element toward and is spaced a predetermined axial distance from said one element; at least one ofvv said first` and second mentioned connectingv means being operable to release itsassociated clutch part for axial contracting* movement of the latter'relative to the other f said' clutch parts, so thatupon separation of both of said connecting means said inner and outer clutch parts may be moved, in axially contracted condition, radially out of the space between said driving and driven elements; selectivelyengageable and disengageable clutch means operatively interposed between said inner and outer clutch parts andV adapted to accommodate said axial contracting and expanding movement of said inner and outer clutch parts; loading meansv for said clutch means mounted for radial movement in unison with said innerl and outer clutch parts out of said space; and a control mechanism for said loading means comprisingV a clutch throw-out collar having a hub portion axially outside of said space and a thrust trans-- mitting portion extending axially from said hub portion` into cooperative engagement with said loading means, and bearingv means connecting said hub portion of said throw-out collar in radial load transmitting andi axially shiftable relation to said support independently of said inner and outer clutch parts.

5. A clutch installation as set forth in claim 4, in which said control mechanism comprises means mounting said throw-out collar on one of said' driving and driven elements for rotation therewith and for axial back and forth movement relative thereto, a cage element supportedly'mounted on said collar in rotatively loose and? ing radially of the axisl of said pivot means in` one direction and a lever arm extendingl radially of the axis of said pivot means in the opposite direction, andy a stationary abutment mounted on said support in the path of swinging movement of' said lever arm and contactable by a portion of the latter at a predetermined radial spacing from the axis of said pivot means upon swinging movement of saidshift element on said axis of said pivot means in one direction.

6. A clutch installation as setA forth in claim 5, in which said throw-out collar has thrustngers; projecting axially atV one side of said shift ele'- ment, and in which said' stationary abutment is mounted on said support in confronting relation to, the other side of said shift element.

7. A clutch installation for motorvehicles comprising, in combination, a pair ofA axially spaced driving andv driven shafts mounted for relative. rotation about a common axis and inA axially fixed relation. to each other, axially fixed driving and driven hub members connected, respectively, withV said shafts at the relatively opposed and axially spaced ends ofthe latter, a friction clutch unit adapted for radial movement into. and out of the space between said hub members and comprisi-ng; axially overlapping inner and outer clutch drums each having an axial length shorter than the axial spacing between said shafts and shorter: than the axial spacingbetween the axial-- ly inner sides of said hub members, an assembly of selectively engageable and dsengageable annular clutch plates mounted on said inner drumv in surrounding relation thereto and at a Dre-V determined axial spacing from one end of the latter, axially separable centering means integrally formed, respectively, with said one end of said inner drum and with one of said hub members and cooperative with each other to radially position said inner drum in `accurately concentric relation with Said common axis at the axially inner side of said one hub member, drive transmitting means operatively connecting said outerA drum at its inner periphery inaxially shiftable relation with said clutch plate assembly, said' outer drum havingv an end portion which in an axially adjusted operative position of said outer drum projects axially beyond said. clutch plate assembly and beyond the free end of said inner drum, and said drive transmitting meansv permittingshifting'movement of said outer drum from. said axially adjusted position toward said one end of said inner drum, axially separable centeringV means integrally formed, respectively, with said one end of said outer drum and with the other ofsaid hub members and cooperative with each otherA to radially' position said outer drum in accurately concentric, relation with said common axis at the axially inner side of said other hub member.; detachable fastening means for securing said inner drum in axially xed positi'on on said one hub member, detachable fastening meansv fory securing said outer drum in said axially adjusted position thereof on said other hub-member, and a control mechanism for said clutch unit: comprising a throw-out collar having a hub portion surrounding one of said driving and driven shafts, anda thrust transmitting portion extendingV from said hub portion toward the other of said driving and driven shafts, bearing' means operatively interposed between said hub portion and said one shaft in nonobstructing relation to said space and accommodating axial back and forth shifting movement of said throw-out collar, and clutch release means disposed within said space for actuation by said thrust transmitting portion of said throwout collar.

WILLIAM F. WILSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 671,602 Levalley Apr. 9, 1901 920,841 Duryea et al. Mar. 4, 1909 1,009,702 Utz Nov. 21, 1911 1,305,020 Tibbetts May 27, 19.19 1,675,703 Grade July 3, 1928 11,803,077 Spaser Apr. 28, 1931 2,157,429 Padden May 9, 1939 2,197,289 Baker et al. Apr. 16, 1940 2,403,322 Acton July 2, 1946 OTHER .REFERENCES Catalog C., (l2-form 6289, page 18, published by Caterpillar Tractor Co Peoria, Illinois. Title, The Caterpillar Diesel D-7 Tractor. 

